[PATCH 6.4 776/800] fs: no need to check source

Greg Kroah-Hartman
2023-07-16T20:29:09Z

From: Jan Kara <jack@suse.cz>

commit 66d8fc0539b0d49941f313c9509a8384e4245ac1 upstream.

The @source inode must be valid. It is even checked via IS_SWAPFILE()
above making it pretty clear. So no need to check it when we unlock.

What doesn't need to exist is the @target inode. The lock_two_inodes()
helper currently swaps the @inode1 and @inode2 arguments if @inode1 is
NULL to have consistent lock class usage. However, we know that at least
for vfs_rename() that @inode1 is @source and thus is never NULL as per
above. We also know that @source is a different inode than @target as
that is checked right at the beginning of vfs_rename(). So we know that
@source is valid and locked and that @target is locked. So drop the
check whether @source is non-NULL.

Fixes: 28eceeda130f ("fs: Lock moved directories")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202307030026.9sE2pk2x-lkp@intel.com
Message-Id: <20230703-vfs-rename-source-v1-1-37eebb29b65b@kernel.org>
[brauner: use commit message from patch I sent concurrently]
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/namei.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4872,8 +4872,7 @@ int vfs_rename(struct renamedata *rd)
d_exchange(old_dentry, new_dentry);
}
out:
- if (source)
- inode_unlock(source);
+ inode_unlock(source);
if (target)
inode_unlock(target);
dput(new_dentry);